Steer-by-wire system and method for operating a steer-by-wire system

Abstract

A steer-by-wire system for a land vehicle, having a steering wheel, a feedback actuator, a detection device equipped to detect a driver's intention to enter the vehicle and/or a driver's intention to exit the vehicle, and an electronic control system, which, following detection of the intention to enter the vehicle and/or the intention to exit the vehicle controls the feedback actuator to hold the steering wheel in a predetermined rotational position by generating a holding torque. When an actuating torque which exceeds the holding torque is applied manually to the steering wheel and the steering wheel is rotated out of the predetermined rotational position, the electronic control system continuously approximates a turning angle of the predetermined rotational position to a turning angle of a current rotational position of the steering wheel using a specified time-based adjustment function based on a difference between the actuating torque and the holding torque.

What is claimed is: 
     
       1. A steer-by-wire system for a vehicle, the steer-by-wire system comprising:
 a steering wheel; 
 a feedback actuator connected to the steering wheel; 
 a detection device equipped to detect a driver's intention to enter the vehicle and/or a driver's intention to exit the vehicle; and 
 an electronic control system, which, following detection of the intention to enter the vehicle and/or the intention to exit the vehicle, is equipped to electrically control the feedback actuator to hold the steering wheel in a predetermined rotational position by generating a holding torque, wherein when an actuating torque which exceeds the holding torque is applied manually to the steering wheel and the steering wheel is consequently rotated out of the predetermined rotational position, the electronic control system is equipped to continuously approximate a turning angle of the predetermined rotational position to a turning angle of a current rotational position of the steering wheel using a specified time-based adjustment function on the basis of a difference between the actuating torque and the holding torque. 
 
     
     
       2. The steer-by-wire system according to  claim 1 , wherein following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, the electronic control system is equipped to set a current rotational position of the steering wheel as a predetermined rotational position. 
     
     
       3. The steer-by-wire system according to  claim 1 , wherein following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, the electronic control system is equipped to set a rotational position of the steering wheel which is associated with a current steering position of at least one steerable road wheel of the land vehicle as a predetermined rotational position. 
     
     
       4. The steer-by-wire system according to  claim 1 , wherein after the approximation of the predetermined rotational position to the current rotational position and when the actuating torque is no longer applied to the steering wheel, the electronic control system is equipped to continuously approximate the turning angle of the current predetermined rotational position to the turning angle of the original predetermined rotational position using a specified time-based reset function. 
     
     
       5. The steer-by-wire system according to  claim 1 , wherein the vehicle is a land vehicle. 
     
     
       6. A steer-by-wire system for a land vehicle, the steer-by-wire system comprising:
 a steering wheel; 
 a feedback actuator connected to the steering wheel; 
 a detection device equipped to detect a driver's intention to enter the vehicle and/or a driver's intention to exit the vehicle; and 
 an electronic control system, which, following detection of the intention to enter the vehicle and/or the intention to exit the vehicle, is equipped to electrically control the feedback actuator to hold the steering wheel in a predetermined rotational position by generating a holding torque, wherein when an actuating torque which exceeds the holding torque is applied manually to the steering wheel and the steering wheel is consequently rotated out of the predetermined rotational position, the electronic control system is equipped to continuously approximate a turning angle of the predetermined rotational position to a turning angle of a current rotational position of the steering wheel using a specified time-based adjustment function on the basis of a difference between the actuating torque and the holding torque, wherein following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, the electronic control system is equipped to set a current rotational position of the steering wheel as a predetermined rotational position, and wherein following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, the electronic control system is equipped to set a rotational position of the steering wheel which is associated with a current steering position of at least one steerable road wheel of the land vehicle as a predetermined rotational position. 
 
     
     
       7. The steer-by-wire system according to  claim 6 , wherein after the approximation of the predetermined rotational position to the current rotational position and when the actuating torque is no longer applied to the steering wheel, the electronic control system is equipped to continuously approximate the turning angle of the current predetermined rotational position to the turning angle of the original predetermined rotational position using a specified time-based reset function. 
     
     
       8. A method for operating a steer-by-wire system of a vehicle, the method comprising:
 detecting a driver's intention to enter the vehicle and/or a driver's intention to exit the vehicle; 
 following detection of the intention to enter the vehicle and/or the intention to exit the vehicle, holding a steering wheel of the steer-by-wire system in a predetermined rotational position by use of a feedback actuator of the steer-by-wire system through the generation of a holding torque, which feedback actuator is connected to the steering wheel; and 
 when an actuating torque which exceeds the holding torque is applied manually to the steering wheel and the steering wheel is consequently rotated out of the predetermined rotational position, continuously approximating a turning angle of the predetermined rotational position to a turning angle of a current rotational position of the steering wheel using a specified time-based adjustment function on the basis of a difference between the actuating torque and the holding torque. 
 
     
     
       9. The method according to  claim 8  further comprising following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, setting a current rotational position of the steering wheel as a predetermined rotational position. 
     
     
       10. The method according to  claim 8  further comprising following detection of the driver's intention to enter the vehicle and/or the driver's intention to exit the vehicle, setting a rotational position of the steering wheel which is associated with a current steering position of at least one steerable road wheel of the land vehicle as a predetermined rotational position. 
     
     
       11. The method according to  claim 8  further comprising after the approximation of the predetermined rotational position to the current rotational position and when the actuating torque is no longer applied to the steering wheel, continuously approximating the turning angle of the current predetermined rotational position to the turning angle of the original predetermined rotational position using a specified time-based reset function. 
     
     
       12. The method according to  claim 8 , wherein the vehicle is a land vehicle.